(3R,4S)-7-hydroxymethyl-2,2,9-trimethyl-4-(phenethylamino)-3,4-dihydro-2H-pyrano[2,3-g]quinolin-3-ol (hereinafter, called as Compound (1)) of Formula (1):
exerts an antiarrhythmic action and the possibility thereof to be used as a drug is known.
Drugs are desired to provide a compound having a constant quality with which a constant effectiveness can be always expected, and are thus generally crystallized. In addition, by crystallizing a compound, there can be obtained such an advantage that the chemical stability of the compound is enhanced (for example, see Non-patent Document 1). Meanwhile, it is known that a solid material has an ability that two or more crystallographic structures different from each other can be taken. The two or more crystallographic structures of the material as described above are called crystal polymorphism. In addition, when a compound is crystallized in an organic solvent or water, it is also known that the organic solvent or water used for the crystallization is sometimes incorporated in the compound, so that the compound becomes a solvate crystal (solvate) or a hydrate crystal (hydrate). In the present specification, the crystal polymorphism together with the solvate crystal and the hydrate crystal are called as crystal forms. These crystal forms usually have different solubilities, dissolution rates, stabilities, hygroscopicities, melting points, handling properties, and the like, so that for developing a crystal of a compound as a drug, it is necessary to evaluate these characteristics comprehensively and to select a crystal form suitable for the development of the drug (for example, see Non-patent Document 2).
However, with respect to Compound (1), there is hitherto only a description that the compound is obtained by the purification using column chromatography and the crystal form of Compound (1) is unknown (for example, see Patent Document 1). It is necessary to confirm whether the compound is able to be crystallized and have crystal forms. Then, when the crystal forms exist, it is necessary to confirm the reproducible production methods of chemically stable crystal forms, and novel crystal forms of the compound.